There is a requirement to restrict the extent to which a sash or casement window can be opened, partly to prevent children opening a window beyond a certain distance so that they cannot fall out through the window, and partly from an anti-theft point of view, to prevent the window being opened from the outside.
However any such restrictor needs to be capable of being overridden when the window is to be fully opened by an adult, from the inside. Such an override mechanism needs to be easily and quickly operable by a user in an emergency but also needs to be complicated enough to prevent the easy operation by a child and to prevent the accidental operation by a person or animal.
It is an object of the present invention to overcome at least one problem associated with prior art devices whether referred to herein or otherwise.